The most telling detail about the current state of TV drama is that, within living memory, it used to be habitual for the Brits to patronise American television fiction. The yanks were OK for glossy shows about cops with a distinctive physical characteristic – bald Kojak, fat Cannon, wheelchair-user Ironside – but the serious stuff was made here: classy costume dramas, the bold and campaigning Play for Today.

Viewers, reviewers and executives who remember when the phrase "wall-to-wall Dallas" served as a terrible warning of the possible consequences of the Americanisation of British drama regard the current era with astonishment. Now an envy of American television drama is one of the governing emotions at UK networks, while polls of the greatest ever shows are dominated by The Sopranos, Mad Men, The Wire, The West Wing and other awe-inspiring imports.

And, revealingly, the three most depressing aspects of our home-grown programming all stand in stark contrast to the situation in the US – under-representation of ethnic minorities, short runs, and uniformity.

Yet against these depressing tendencies can be set reasons to be cheerful about British small-screen fiction – including the joy of ad-free TV, the standard of acting, and hits such as last summer's Sherlock.

The weaknesses of British television

Race: Although sparked by accident, through a comment in an interview, the row over the almost wholly white casting in ITV1's Midsomer Murders has fortuitously exposed a crisis in British television. The dominance of dramas set either in the actual past (all those Austen and Dickens adaptations) or a make-believe present (such as Midsomer) means that our drama is often criminally unrepresentative and star acting talent – Adrian Lester, Sophie Okonedo, Chiwetel Ejiofor – is driven to America for better parts.

Series length: American TV companies have the courage and funding to back the big vision: committing to 20-episode runs with quick-fire options on further runs. In the UK, partly because of the tradition of single authorship rather than team-writing, commissioning is too often short and cautious, so that when a hit emerges – Sherlock, Downton Abbey – enthusiastic viewers/advertisers have a very lengthy wait for more. Yet, paradoxically, once a franchise is established, we're too loath to let it go, even when (Taggart, Silent Witness, Midsomer) the central actors leave.

Uniformity: And then there is the problem of uniformity. Literally so. It seems almost obligatory for UK drama series to involve either cops or docs: even Peter Bowker, one of our most original writers, has succumbed to the surgical-procedural with Monroe. Yet notice that the fabled recent American series have unconventional settings (a funeral parlour, a 1960s ad agency, the White House) or unexpected heroes: mafia gangster, corrupt politicians and cops.

The strengths of British television

Sherlock: As yet another adaptation of our most famous detective, Sherlock sounded potentially conservative. Yet the series combined high-class plot and dialogue from Steven Moffat and Mark Gatiss, with visually innovative direction and smart casting – including spotting that Benedict Cumberbatch was on the cusp of greatness – to create a drama that combined British tradition with American pizzazz.

Kudos: Despite recent sci-flop Outsiders, Stephen Garrett's and Jane Featherstone's independent production company remains aptly named, having re-energised TV drama in recent years with high-gloss, high-concept series including Life on Mars, Ashes to Ashes, Hustle and Spooks. The latter, in particular, has shown how to combine compelling narratives with serious political and psychological ideas, while consistently refreshing a long-running franchise.

Acting: One of the joys of watching UK TV dramas is the sheer depth of acting talent available: from veterans (Sheila Hancock, Ian McKellen, Derek Jacobi) through the generation heading for knighthoods (Simon Russell Beale) to the younger set who immediately impress (Hattie Morahan, Benedict Cumberbatch). With the single exception of racial inequality – see above – casting options in Britain are consistently greater than in the US.

Realism: Ever since Play for Today and the early work of Ken Loach and Mike Leigh, British TV fiction has led the way in quasi-documentary or journalistic pieces. The biggest weakness of the American product is that almost everything tends towards a high gloss. In the UK, the greater strength of television documentary sees directors – most recently, Peter Kosminsky with Channel 4's The Promise – applying their factual background to fiction.

Ad-free TV: Although much great TV drama, in both the US and the UK, has been screened with commercial interruptions, creating a narrative that climaxes every quarter of an hour is a challenge to writers, actors and viewers. Authors and audiences here are lucky to have, at the BBC, the opportunity of following a story straight through, without a break.